Xanthene derived dyes are known to be efficient fluorescent dyes. Functional groups on the conjugated moiety of the dye (chromophore) have the ability to fine tune the dye's fluorescent colors.
Some xanthene derived dyes are the Rhodamine dyes. These compounds can be regarded as diaminated analogs of xanthene (at the positions 6′ and 3′; see below for further elaboration on the numbering convention of rhodamine) which has been also arylated at the 9′ position. Rhodamines fluoresce have been used extensively in research, both as free dye and as conjugates to larger molecules, e.g. proteins and antibodies as biomarkers.

Rhodamines are outstanding versatile organic dyes. They demonstrate thermal and photochemical stability, strongly absorb visible light, and show high fluorescence quantum yields. Rhodamine based compounds have been utilized as industrial dyes, electronic materials, medical devices, bio markers, lighting devices, sensors and photovoltaics. Within the rhodamine family of compounds, one of the commonly used fluorescent rhodamine dye is rhodamine 6G (other examples include sulforhodamine 101 and rhodamine 101) which has high quantum yield and high photostability, rendering it a suitable compound in optical and electro optical applications, as well as biotechnological applications.
There is a significant need for new fluorescent dyes with superior optical and electro optical parameters such as fluorescence intensity, quantum yield and photostability, as basis for novel (bio)optical and (bio)electro-optical devices.